1. Field of the Invention
The present invention relates to a refrigerant evaporator which is constructed by laminating a plurality of tubes made of a couple of metal thin plates having a first refrigerant passage, a second refrigerant passage and four tank portions at their upper and lower ends.
2. Description of Related Art
The inventors of the present invention have disclosed a refrigerant evaporator 1 having a refrigerant route as shown in FIG. 4 in Japanese Patent Application No. 9-22844. In the evaporator 1, an inlet side heat exchanging portion 3a is formed at an air down stream side, and an outlet side heat exchanging portion 3b is formed at an air upstream side. Here, an arrow A denotes an air flow direction. The inlet side heat exchanging portion 3a communicates with an upper side inlet tank portion 47 and a lower side inlet tank portion 48. The outlet heat exchanging portion 3b is communicated with an upper side outlet tank portion 43 and a lower side outlet tank portion 44. In the heat exchanging portions 3a and 3b, a heat exchange between refrigerant flowing in the evaporator 1 and the air is carried out. The lower side inlet tank portion 48 is separated into a first inlet tank portion "a" and a second inlet tank portion "b" by a partition plate 51. The upper side outlet tank portion 43 is separated into a first outlet tank portion "c" and a second outlet tank portion "d".
In the evaporator 1, as show in FIG. 9, a tube 2 through which the refrigerant flows is constructed by connecting a couple of metal plates 4 to face each other. An inside of the tube 2 is partitioned into an outlet side (air upstream side) refrigerant passage 2a and an inlet side (air downstream side) refrigerant passage 2b by a center rib 49. At both upper and lower ends of the tube 2, tank portions 47, 48, 43 and 44 which communicate with the refrigerant passages 2a and 2b are formed into a shape like a columnar concave. In each tank portion 47, 48, 43 or 44, communication holes 45, 46, 41 and 42 which connect the tank portions 47, 48, 43 and 44 of adjacent tubes 2 are formed.
In FIG. 4, the refrigerant flows inside the evaporator 1 in accordance with the following route;
"inlet pipe 8a.fwdarw.inlet side communicating portion 15.fwdarw.first inlet tank portion "a".fwdarw.inlet side refrigerant passages 2a.fwdarw.upper side inlet tank portion 47.fwdarw.inlet side refrigerant passages 2a.fwdarw.second inlet tank portion "b".fwdarw.refrigerant passage 13.fwdarw.first outlet tank portion "c".fwdarw.outlet side refrigerant passages 2b.fwdarw.lower side outlet tank portion 44.fwdarw.outlet side refrigerant passages 2b.fwdarw.second outlet tank portion "d" outlet side communicating portion 14.fwdarw.refrigerant outlet pipe 8b". Here, the inlet pipe 8a and the outlet pipe 8b is connected to the left side of the evaporator 1. The inlet side communicating portion 15 and the outlet side communicating portion 14 are formed at the left side of the evaporator 1. The refrigerant passage 13 is formed at the right side of the evaporator 1.
In this way, with respect to the air flow A, the outlet side heat exchanging portion 3b is disposed at the air upstream side, and the inlet side heat exchanging portion 3a is disposed at the air downstream side. In the inlet side heat exchanging portion 3a and the outlet side heat exchanging portion 3b, the refrigerant flows in the same direction. That is, in FIG, 4, at the right side of the partition plates 51 and 52 in the heat exchanging portions 3a and 3b, the refrigerant flows downwardly, while at the left side of the partition plates 51 and 52, the refrigerant flows upwardly.
The evaporator 1 is manufactured by laminating the metal plate 4 made of aluminum as shown in FIG. 9 to assemble an evaporator structure and brazing it in the brazing furnace. When the evaporator structure is temporarily assembled, the coupled metal plates 4 facing each other are not to be set off with each other, because the contacting area therebetween is comparatively large for they contact each other at the outer peripheries of the metal plate 4 and the center rib 49. However, the metal plates 4 being adjacent to each other tend to be set off, because the contacting area therebetween is small for they contact each other at only the protruded surfaces of their tank portions 43, 44, 47 and 48.